This invention relates generally to a pneumatic radial tire for use in a motorcycle, and more particularly to a pneumatic radial tire for a motorcycle in which a cord reinforcing layer is disposed outside a carcass layer of a side wall of the tire in such a fashion that at least one of the end portions of the cord reinforcing layer are stacked with the end portions of belt reinforcing layers, and is turned up around a bead core, in order to improve the driving stability of the motorcycle at the time of cornering.
Tires of a radial structure in general are more excellent than tires of a bias structure in the aspects of abrasion resistance, straight driving stability, cornering performance and fuel consumption, and are widely used as the tires for four-wheel automobiles. When used as the tires for a motorcycle, however, the tires of the radial structure involves the problem of low driving stability required at the time of cornering, and are therefore believed unsuitable for the motorcycle. In other words, tires of a motorcycle generates a large camber angle at the time of cornering, and a side force to match with this camber angle is necessary. In the tires of the radial structure, the cord angle of a carcass layer is substantially 90.degree. in the circumferential direction of the tires, so that a sufficiently high side force cannot be obtained when compared with tires of the bias structure. This results in the problems that the oscillation of the frame of the motorcycle occurs at the time of cornering to reduce the driving stability of the motorcycle.